1. Field of Technology
The present invention generally relates to an electrophotographic copying machine and, more particularly, to the copying machine utilizing a photoreceptor in the form of an endless belt. 2. Description of the Prior Art
A copying machine utilizing a photoreceptor belt is well known. It is well known that this type of copying machine could be manufactured compact in size by disposing around and adjacent the photoreceptor belt all necessary processing units including a charger means, means for introducing imagewise light carrying an image of the original, a developer means, a transfer means and others. In addition, if one of the two support rolls over which the photoreceptor belt is trained is reduced in radius and a transfer charger is disposed in the vicinity of such one of the support rolls, not only can a powder image be transferred from the photoreceptor belt onto a copying paper, but also the copying paper can readily be separated naturally from the photoreceptor belt. The copying paper so separated with the powder image thereon is subsequently conveyed towards a fixing station. If these advantages peculiar to the photoreceptor belt are utilized, it is possible to shorten the belt length, to pack all of the necessary processing units in the vicinity of the photoreceptor belt, to reduce the radius of one of the support rolls and to dispose a fixing roll adjacent such one of the support rolls for facilitating the conveyance of the copying paper, separated from the photoreceptor belt, onto the fixing roll. In this way, the copying machine as a whole can be assembled in a compact size.
However, when the copying machine is assembled in a compact size in the manner described above, the surroundings of the fixing roll tend to be heated by heat generated from the fixing roll and will attain an elevated temperature when the copying machine itself is held in a standby, or READY, condition. Once this happens, the electroconductivity of the photoreceptor is adversely affected by a change in temperature to such an extent as to differentiate the surface potential at a dark area from that at a bright area, resulting in the possibility that the resultant copy would represent a reproduced image of varying image density.
In order to obviate the above discussed problem, it may be contemplated to arrange the fixing roll spaced a sufficient distance from the photoreceptor belt. However, this method does not contribute to reduction in size of the copying machine as a whole which ought to be achieved by the use of the photoreceptor belt.